Sodium requirement of adult cats for maintenance based on plasma aldosterone concentration.
The sodium requirement of adult cats for maintenance was determined using a randomized block design of eight dietary sodium treatments (0.1, 0.4, 0.5, 0.66, 0.8, 1.2, 1.6 or 2.0 g Na/kg in a casein-lactalbumin-based purified diet) administered for periods of 4 wk. A total of 35 adult specific-pathogen-free domestic shorthaired cats (26 males and 9 females, 1.5-3 y of age) was given an equilibration diet (2 g Na/kg) for 14 d before assignment (or reassignment) to the treatments. A total of 12 cats (8 males, 4 females) was randomly assigned to the lowest six levels of sodium, and four cats to the highest two sodium levels. Cats consuming the diet containing 0.1 g Na/kg had significantly elevated aldosterone concentration in plasma, and packed cell volume. In addition, these cats exhibited anorexia, body weight loss, reduced urinary specific gravity and sodium excretion, and had a negative sodium balance. However, adult cats did not develop polydypsia and polyuria reported in sodium-deficient kittens. Cats given the diet containing 0.66 g Na/kg did not have an increased packed cell volume, but aldosterone concentration in the plasma was significantly elevated. However, cats given diets containing >/=0.8 g Na/kg had plasma aldosterone concentrations +info)
Assessment of swallowing and referral to speech and language therapists in acute stroke.
The best clinical assessment of swallowing following acute stroke, in order to decide whether to refer a patient to a speech and language therapist (SLT), is uncertain. Independently of the managing clinical team, we prospectively investigated 115 patients (51 male) with acute stroke, mean age 75 years (range 24-94) within 72 h of admission, using a questionnaire, structured examination and timed water swallowing test. Outcome variables included referral to and intervention by a speech and language therapist (SLT), dietary modification, respiratory complications and death. Of those patients in whom an SLT recommended intervention, 97% were detected by an abnormal quantitative water swallowing test; specificity was 69%. An SLT was very unlikely to recommend any intervention if the test was normal. Inability to perform a water test and/or abnormality of the test was associated with significantly increased relative risks of death, chest infection and dietary modification. A timed water swallowing test can be a useful test of swallowing and may be used to screen patients for referral to a speech and language therapist after acute stroke. (+info
Effect of meat (beef, chicken, and bacon) on rat colon carcinogenesis.
High intake of red meat or processed meat is associated with increased risk of colon cancer. In contrast, consumption of white meat (chicken) is not associated with risk and might even reduce the occurrence of colorectal cancer. We speculated that a diet containing beef or bacon would increase and a diet containing chicken would decrease colon carcinogenesis in rats. One hundred female Fischer 344 rats were given a single injection of azoxymethane (20 mg/kg i.p.), then randomized to 10 different AIN-76-based diets. Five diets were adjusted to 14% fat and 23% protein and five other diets to 28% fat and 40% protein. Fat and protein were supplied by 1) lard and casein, 2) olive oil and casein, 3) beef, 4) chicken with skin, and 5) bacon. Meat diets contained 30% or 60% freeze-dried fried meat. The diets were given ad libitum for 100 days, then colon tumor promotion was assessed by the multiplicity of aberrant crypt foci [number of crypts per aberrant crypt focus (ACF)]. The ACF multiplicity was nearly the same in all groups, except bacon-fed rats, with no effect of fat and protein level or source (p = 0.7 between 8 groups by analysis of variance). In contrast, compared with lard- and casein-fed controls, the ACF multiplicity was reduced by 12% in rats fed a diet with 30% bacon and by 20% in rats fed a diet with 60% bacon (p < 0.001). The water intake was higher in bacon-fed rats than in controls (p < 0.0001). The concentrations of iron and bile acids in fecal water and total fatty acids in feces changed with diet, but there was no correlation between these concentrations and the ACF multiplicity. Thus the hypothesis that colonic iron, bile acids, or total fatty acids can promote colon tumors is not supported by this study. The results suggest that, in rats, beef does not promote the growth of ACF and chicken does not protect against colon carcinogenesis. A bacon-based diet appears to protect against carcinogenesis, perhaps because bacon contains 5% NaCl and increased the rats' water intake. (+info
Nitrogen retention by lambs fed oscillating dietary protein concentrations.
Nitrogen excreted by beef cattle can be retained in manure or lost by volatilization to the atmosphere or by runoff and percolation into surface or ground water. Increasing the retention of dietary N should decrease environmental losses. To this end, the effects of oscillating concentrations of dietary CP on nutrient retention were determined using lambs fed a 90% concentrate diet. Ten St. Croix lambs (average BW = 27 kg) were used in two 5x5 Latin square experiments. Dietary treatments were as follows: 1) 10% CP, 2) 12.5% CP, 3) 15% CP, 4) 10% and 15% CP diets oscillated at 24-h intervals, and 5) 10% and 15% CP diets oscillated at 48-h intervals. Supplemental N was provided by cottonseed meal in Trial 1 and by a 50:50 (N basis) blend of cottonseed meal and urea in Trial 2. Each period of the Latin square lasted 35 d, with excreta collection the final 8 d. Nitrogen retention increased linearly (P<.01) with increasing N intake in both trials (.77, 1.33, and 1.89 g/d for 10, 12.5, and 15% CP, respectively, in Trial 1; .94, 1.78, and 2.19 g/d for 10, 12.5, and 15% CP, respectively, in Trial 2). Compared with continuously feeding the 12.5% CP diet, oscillating the 10 and 15% CP diets on a 24-h basis did not affect N retention (P>.10) in either trial (1.62 and 1.56 g/d for Trials 1 and 2, respectively). Oscillating dietary CP at 48-h intervals did not affect N retention in Trial 2 (1.82 g/d) but increased (P<.05) N retention by 38% in Trial 1 (1.87 g/d). Phosphorus, K, and Na retention and excretion were not affected by dietary treatments in Trial 1. In Trial 2, P retention increased (linear, P<.05) with increasing dietary CP and was greater (P<.05) in lambs on the 48-h oscillation treatment than in lambs fed the 12.5% CP diet. These results suggest that oscillating the dietary CP concentrations might potentially increase the utilization of N by ruminants fed high-concentrate diets. (+info
Effect of individual or combined ablation of the nuclear groups of the lamina terminalis on water drinking in sheep.
The subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT), and median preoptic nucleus (MnPO) were ablated either individually or in various combinations, and the effects on drinking induced by either intravenous infusion of hypertonic 4 M NaCl (1.3 ml/min for 30 min) or water deprivation for 48 h were studied. Ablation of either the OVLT or SFO alone did not affect drinking in response to intravenous 4 M NaCl, although combined ablation of these two circumventricular organs substantially reduced but did not abolish such drinking. Ablation of the MnPO or MnPO and SFO together also substantially reduced, but did not abolish, drinking in response to intravenous hypertonic NaCl. Only near-total destruction of the lamina terminalis (OVLT, MnPO, and part or all of the SFO) abolished acute osmotically induced drinking. The large lesions also reduced drinking after water deprivation, whereas none of the other lesions significantly affected such drinking. None of these lesions altered feeding. The results show that all parts of the lamina terminalis play a role in the drinking induced by acute increases in plasma tonicity. The lamina terminalis appears to play a less crucial role in the drinking response after water deprivation than for the drinking response to acute intravenous infusion of hypertonic saline. (+info
Use of doxycycline-controlled gene expression to reversibly alter milk-protein composition in transgenic mice.
A reverse tetracycline transactivator-encoding cDNA under the control of the mammary specific beta-lactoglobulin promoter was linked to a bovine alpha-lactalbumin transcription unit driven by a reverse tetracycline-controlled transactivator/doxycycline-inducible human cytomegalovirus promoter. The construct was microinjected into eggs from alpha-lactalbumin-deficient mice. These mice produce a highly viscous lactose-free milk and have a shortened lactation period. Mice from three out of the nine transgenic lines investigated expressed reverse tetracycline-controlled transactivator mRNA in their lactating mammary glands at levels detectable by Northern analysis. Following doxycycline addition to the drinking water, lactation was fully restored in animals from the three lines. Doxycycline removal resulted in a reversal of phenotype. The observed mammary-specific and high expression of the doxycycline inducible reporter gene (up to 5.2 mg of recombinant alpha-lactalbumin.mL-1 of milk, i.e. up to 13-fold induction) opens up exciting prospects to use the tetracycline system to study the development and functioning of the mammary gland, and to control the production level of active pharmaceutical proteins in the milk of transgenic animals. (+info
Effect of prolonged administration of a urinary kinase inhibitor, ebelactone B on the development of deoxycorticosterone acetate-salt hypertension in rats.
The effect of prolonged administration of a carboxypeptidase Y-like kininase inhibitor, ebelactone B (EB) (2-ethyl-3, 11-dihydroxy-4, 6, 8, 10, 12-pentamethyl-9-oxo-6-tetradecenoic 1, 3-lactone), on the development of deoxycorticosterone acetate (DOCA)-salt hypertension was tested. The systolic blood pressure (SBP) of non-treated 6-week-old Sprague-Dawley strain rats was gradually increased by DOCA-salt treatment from 137+/-2 mmHg (n=11) to 195+/-7 mmHg at 10 weeks of age. With daily oral administration of lisinopril (5 mg kg(-1), twice a day), which is an inhibitor of angiotensin converting enzyme, a major kininase in plasma, the development of hypertension was not suppressed. By contrast, administration of EB (5 mg kg(-1), twice a day), completely inhibited the development of hypertension (SBP: 146+/-1 mmHg, n=5, 10 weeks old). The reduced SBP at 10 weeks of age was equal to the SBP before any treatment (142+/-1 mmHg, n=5). Direct determination of mean blood pressure (MBP) in conscious, unrestrained rats confirmed that MBP elevation was completely inhibited by EB. Continuous subcutaneous infusion (5 mg kg(-1) day(-1)) of HOE140, a bradykinin B2 receptor antagonist, restored the elevation of SBP, which was suppressed by EB. The weights of left ventricle of DOCA-salt treated rats 10-weeks-old (0.36+/-0.02 g 100 g body weight(-1), n=11) was significantly reduced by EB (0.27+/-0.01, n=5), as were the sodium levels in serum, cerebrospinal fluid and erythrocyte. These findings suggested that EB is effective in preventing salt-related hypertension presumably by eliminating sodium retention. (+info
Long-term CCK-leptin synergy suggests a role for CCK in the regulation of body weight.
The gut peptide CCK is a nutrient-related signal important to the control of food intake. In the present studies, we observed that a single intraperitoneal injection of CCK (1-2 microgram/kg) given 2-3 h after intracerebroventricular leptin (2-5 microgram) reduced body weight and chow intake over the ensuing 48 h more than did leptin alone. CCK alone had no effect on either 48-h chow intake or body weight but significantly reduced feeding during a 30-min sucrose test. However, reduction of 30-min sucrose intake by CCK was not enhanced by prior intracerebroventricular leptin. The present data suggest that CCK can contribute to the regulation of body weight when central leptin levels are elevated. (+info